In the field of embroidering machines the state of the art includes the use of devices to automatically apply ribbons or cord thread onto fabrics cut into pieces.
These devices serve to make particular types of embossed embroidery; they work on pieces of a limited length, particularly on pieces worked on the tambour frame, in a discontinuous work pattern which gives limited productivity.
Moreover, the ornamental designs made by these devices are isolated, considerably distant from each other and discontinuous.
When these devices are used the embroidery machines have a very low working speed, in the region of 120 stitches a minute at most.
State of the art devices of this type, as they are used at present, are therefore not suitable for use on electronically controlled machines which continuously work fabric supplied from a roll, with speeds of at least 450 stitches a minute and which can reach up to 600+700 stitches a minute.
Such conventional devices are used only to apply large section cord thread or ribbons or chenille or embroidery thread (therefore unable to pass through the eye of a needle), on a base fabric.
In such devices the ribbons or embroidery threads are not made to pass through the fabric and are not fixed thereon by means of stitches made by needles which perforate them; they are fixed to the fabric by means of the stitches of a thin thread which passes above them and is anchored to the fabric once on one side and once on the opposite side of the embroidery threads (see for example FIG. 1 in CH-A-563.486).
In such devices, for this purpose, suitable wheels are provided equipped with an alternate rotary movement, generally produced by rectilinear racks; each wheel is provided with a central hole through which the needle with the fixing thread passes and an eccentric hole of a suitable diameter, through which passes the cord thread or the embroidery thread which has to be attached on the fabric.
While the needles carrying the fixing thread perform a normal stitching action, the alternating rotations of the wheels cause the cord threads or embroidery threads to be positioned alternately on one side and the other of the needles, and therefore cause the stitches made thereby to pass alternately from one side to the other above the cord threads or embroidery threads, thus fixing them to the fabric.
Among these conventional devices, the one described in CH-A-563.486 describes a device able to modify the position of the eccentric hole though which the embroidery thread passes, according to the orders to move given by an automatic embroidery machine commanded by a perforated belt, according to the rotation of the direction of stitching backwards-forwards-left-right, so that the rotation in one direction and the other of the wheels has its center, on each occasion, in the correlated main direction of stitching backwards-forwards-left-right.
In document FR-A-467.481 there are wheels with pins on the outer circumference, commanded by a perforated flexible belt into the holes of which the pins enter, instead of the rectilinear rack.
However, these documents refer to embroidery machines, not to multi-needle quilting machines.
Quilting machines, as we have said, have a working speed at least in the range of 450 stitches per minute, compared with a maximum speed in embroidery machines of about 120 stitches per minute.
Moreover, whereas in embroidery machines the fabric is cut into pieces, attached manually onto appropriate frames before the embroidery operation, and removed always manually when the work is finished, in quilting machines the fabric or the sandwich of material which is to be quilted is unwound continuously from rolls, with a huge saving in time and effort for the workers.
In embroidery machines the needles work in a horizontal direction, whereas in quilting machines they work in a substantially vertical direction.
In quilting machines there is at least a pressure plate on which the wheels through which the thread passes are mounted, with the respective command organs, whereas in embroidery machines there is no pressure plate whatsoever.
The final products obtained from quilting machines are essentially quilted bed-covers which can also be embroidered, whereas in embroidery machines the final products consist of any type of embroidery or decoration on single-layer fabrics of a decorative type.
Conventional devices, moreover, do not give the possibility of carrying out step by step, with the position of the wheels, the desired program of embroidery; therefore they do not allow to achieve designs of absolute precision with the cord threads, ribbons or additional threads; nor do they allow to alternate on command segments where the cord thread or ribbon is applied with segments of simple stitching to achieve particular ornamental patterns according to a pre-determined sewing program.
In conventional devices, moreover, it is not always possible, at every step of the program, to direct the hole through which the embroidery thread passes perfectly in front of the needle according to the direction of sewing, with discrepancies of a fraction of a degree; nor is it possible to exclude the alternate rotation of the wheels.
This does not allow these conventional devices to sew exactly in the center, whatever may be the direction of sewing, ribbons, tapes and flat trimmings and to attach them on the basic fabric, nor to alternate segments where ribbon or cord thread is applied with segments of simple stitching, thus limiting the applications and possibilities.
The Applicant has devised and embodied this invention in order to overcome this shortcoming of the state of the art, which has never provided or hypothesised applications of this type on multi-needle quilting machines, given the difficulty of using embroidery techniques previously employed only on machines which were operationally and technologically completely different, and to obtain further advantages as shown hereafter.